Optical disc drive focusing apparatus

ABSTRACT

An optical focusing system is configured to generate a data profile, wherein the data profile is configured to provide signals for operation of an actuator. Application of the signals from the data profile results in focus of optics within a label region of an optical disc. An image is printed on the label region of the optical disc while the optics focus on the label region of the optical disc by applying signals to the actuator according to the data profile.

BACKGROUND

Optical discs, such as compact discs (CD) and digital versatile discs(DVD) are a form of computer readable media which provide extensivestorage for digital information. While some optical discs may beread-only, others may additionally be written-to. Typically, one side ofthe disc is referred to as the data side and the other side of theoptical disc is referred to as the label side. The label side mayinclude factory-prepared label text and graphics.

An optical disc drive (ODD) of a computer is used to read from, and incertain cases to write to, the data side of an optical disc. An opticalpickup unit (OPU), included within the optical disc drive, is configuredwith a laser and sensors adapted for reading, and possibly writing,data. Various ODDs and OPUs are available, and are manufactured tospecifically read and write to the data side of optical discs.

Using emerging technology, the OPU assembly may be is used to define animage on the label surface of an optical disc configured for such alabeling process. However, during the labeling process conventionalfocusing systems used within the OPU assembly will not work properly. Anumber of reasons exist for this failure. First, known OPU assemblies inODDs are designed to focus light through a layer of clear polycarbonate,onto a data track defined on top of the layer. As a result, the opticsin known OPUs are designed to compensate for refraction resulting fromlight passage through the polycarbonate. In contrast, when marking thelabel surface, light must be focused directly onto the top of the labelsurface, and does not pass through any layer of transparent material.Accordingly, the corrections built into the optics which cancel therefraction resulting from light travel through the polycarbonate presenta problem when attempting to focus existing OPUs on a label surface.

A second reason for the difficulty encountered in focusing light on thelabel surface of a disc is that conventional OPUs, which are configuredto focus light through the polycarbonate, are effectively designed tofocus light at a distance which is greater than the distance to thesurface of the disc. Accordingly, to focus on the surface of the disc,signals sent to the optics must be reconfigured to focus at the surfaceof the disc, rather than at a more distant location, such as the datatrack within the disc.

A third reason for the difficulty encountered in focusing light on thelabel surface of the disc is that conventional OPUs are configured tofocus on data pits defining a data track, which is typically backed by areflective covering of aluminum. This reflective covering provides avery smooth and uniformly reflective surface, which reflect laser lightuniformly. Sensors which detect the reflected light tend to have a veryhigh signal-to-noise ratio. In contrast, light is not uniformlyreflected off the label surface of the disc, and the sensors whichdetect this reflected light have a very low signal-to-noise ratio.

Accordingly, the need exists for new and improved systems and methods tocontrol focal optics within optical disc drives.

SUMMARY

An optical focusing system is configured to generate a data profile,wherein the data profile is configured to provide signals for operationof an actuator. Application of the signals from the data profile resultsin focus of optics within a label region of an optical disc. An image isprinted on the label region of the optical disc while the optics focuson the label region of the optical disc by applying signals to theactuator according to the data profile.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description refers to the accompanying figures.In the figures, the left-most digit(s) of a reference number identifiesthe figure (Fig.) in which the reference number first appears. Moreover,the same reference numbers are used throughout the drawings to referencelike features and components.

FIG. 1 is a block diagram illustrating an exemplary disc media markingsystem for measuring and calibrating input voltage values to control anactuator for operation of focal optics.

FIG. 2 is a block diagram illustrating an exemplary optical disc drivesystem.

FIG. 3 illustrates various timeline curves that describe calibration forphase delay of input voltage to an actuator.

FIG. 4A is a block diagram illustrating various locations on an opticaldisc where focus measurements may be made to determine contour variancesof the optical disc.

FIG. 4B illustrates various curves associated with relativemeasurements, focus positions, and input voltages plotted againstangular orientation of an optical disc used in measurement of an opticaldisc.

FIG. 5 illustrates relative measurement of an optical disc at variousangular positions and an associated input voltage curve to place opticsat particular positions during a labeling procedure.

FIG. 6A is a block diagram illustrating an exemplary calibration table.

FIG. 6B is a block diagram illustrating an exemplary input voltagelook-up table.

FIG. 7 is a block diagram illustrating an optical disc with exemplarypatterns that are recognizable when a laser beam is in focus.

FIG. 8 is a flow chart illustrating a process for calibration procedure.

FIG. 9 is a flow chart illustrating measurement procedure.

FIG. 10 is a flow chart illustrating a labeling procedure.

DETAILED DESCRIPTION

Overview

The following discussion is directed to systems and methods forproviding signals to focusing optics within an optical disc drive tofacilitate optical disc labeling. By measuring a variety of locations onthe disc, a data profile, such as a table or a function, may be createdassociating a variety of locations on the disc with data, such as avoltage for transmission to an actuator to maintain focus on a labelsurface of the disc. Accordingly, the label surface of the disc may bekept in focus while a label is printed by applying the appropriatevoltages (or current, etc.) to the actuator (e.g. a voice coil motor) toplace the OPU optics (e.g. objective lens) in proper focus whilecompensating for an irregular disc surface.

Exemplary System Environment

FIG. 1 shows an exemplary disc media marking system 100 suitable formeasuring and calibrating input voltage values of an actuator. Themarking system 100 includes a disc media marking device 105 and adisplay device 110. The disc media marking device 105 may be implementedas a stand-alone appliance device for labeling disc media.Alternatively, the disc media marking device 105 may be integrated aspart of an optical media player or drive, such as a writable compactdisc (CD) player which is implemented to label an optical disc as wellas record data onto a CD-R (CD recordable disc) and/or a CD-RW(CD-rewritable disc). Such writable CD devices may include, for example,a stand-alone audio CD player which is a peripheral component in anaudio system, a CD-ROM drive integrated as standard equipment in a PC(personal computer), a DVD (digital versatile disc) player, and anynumber of similar embodiments.

Disc media marking device 105 includes one or more processors 115 (e.g.,any of microprocessors, controllers, and the like) which process variousinstructions to control the operation of disc media marking device 105and communicate with other electronic and computing devices. Disc mediamarking device 105 may be implemented with one or more memorycomponents, examples of which include a random access memory (RAM) 120,a disc storage device 125, and non-volatile memory 130 (e.g., any one ormore of a read-only memory (ROM) 135, flash memory, EPROM, EEPROM,etc.).

Disc storage device 125 may include any type of magnetic or opticalstorage device, such as a hard disc drive, a magnetic tape, a recordableand/or rewriteable compact disc (CD), a DVD, DVD+RW, and the like. Theone or more memory components provide data storage mechanisms to storevarious information and/or data such as configuration information fordisc media marking device 105, graphical user interface information, andany other types of information and data related to operational aspectsof disc media marking device 105. Alternative implementations of discmedia marking device 105 may include a range of processing and memorycapabilities, and may include any number of differing memory componentsthan those shown in FIG. 1.

Disc media marking device 105 includes a firmware component 140 which isimplemented as a permanent memory module stored on ROM 135, or withother components in disc media marking device 105, such as a componentof a processor 115. Firmware 140 is programmed and distributed with discmedia marking device 105 to coordinate operations of the hardware withindisc media marking device 105 and contains programming constructs usedto perform such operations.

An operating system 145 and one or more application programs may bestored in non-volatile memory 130 and executed on processor(s) 115 toprovide a runtime environment. A runtime environment facilitatesextensibility of disc media marking device 105 by allowing variousinterfaces to be defined that, in turn, allow the application programsto interact with disc media marking device 105. In this example, theapplication programs include a label design application 150, an imageprocessing application 155, and a print control application 160.

The label design application 150 generates a label design user interface165 for display on display device 110 from which a user may create alabel image to be rendered on a disc media, such as on an optical disc.A user may specify, or otherwise drag and drop text, a bitmap image forbackground, a digital photo, a graphic or symbol, and/or any combinationthereof to create the label image on the user interface 165.

The image processing application 155 processes the label image createdwith the label design user interface 165 to produce a data stream oflabel image data and laser control data to control rendering the imageon concentric circular tracks of a disc media (i.e., an optical disc).For example, a continuous tone RGB (red, green, and blue) rectangularraster graphic of the label image may be converted to concentriccircular tracks. The curved raster is color mapped and separated intothe printing color channels KCMY (black, cyan, magenta, and yellow), orgrayscale. This data stream is formatted as laser control data and isaugmented with other control commands to control the disc media markingdevice 105 rendering a label on the disc media.

A label file is generated which may be communicated to a controllerwhere the label file is parsed to control a labeling mechanism.Alternatively, the concentric circular tracks may be generated andstreamed to the disc media marking device 105 one track at a time toutilize host processing with the device's rendering process.

The print control application 160 determines the radius of the firsttrack and the subsequent track spacing. After the radius of the firsttrack and the track spacing is determined, the print control application160 determines which label image data will correspond to each respectivetrack. The laser mark locations along a particular track are specifiedin a coordinate system where the concentric circular tracks are definedin coordinates of the radial distance and the distance along eachrespective track.

Disc media marking device 105 includes an optical disc drive (ODD)system 170 which may be implemented to mark on a surface of a disc media(i.e., optical disc), such as to render a label image on a label surface(i.e., label side) of an optical disc. The ODD system 170 is describedin greater detail herein below with reference to FIG. 2.

Disc media marking device 105 further includes one or more communicationinterfaces 175 which may be implemented as any one or more of a serialand/or parallel interface, as a wireless interface, any type of networkinterface, and as any other type of communication interface. A wirelessinterface enables disc media marking device 105 to receive control inputcommands and other information from an input device, such as from aremote control device or from another infrared (IR), 802.11, Bluetooth,or similar RF input device. A network interface provides a connectionbetween disc media marking device 105 and a data communication networkwhich allows other electronic and computing devices coupled to a commondata communication network to send label image data and otherinformation to disc media marking device 105 via the network. Similarly,a serial and/or parallel interface provides a data communication pathdirectly between disc media marking device 105 and another electronic orcomputing device.

Disc media marking device 105 may include user input devices 180 whichmay include a keyboard, pointing device, selectable controls on a usercontrol panel, and/or other mechanisms to interact with, and to inputinformation to disc media marking device 105. Disc media marking device105 also includes an audio/video processor 185 which generates displaycontent for display on display device 110, and generates audio contentfor presentation by a presentation device, such as one or more speakers(not shown). The audio/video processor 185 may include a displaycontroller which processes the display content to display correspondingimages on display device 110. A display controller may be implemented asa graphics processor, microcontroller, integrated circuit, and/orsimilar video processing component to process the images. Video signalsand audio signals may be communicated from disc media marking device 105to display device 110 via an RF (radio frequency) link, S-video link,composite video link, component video link, or other similarcommunication link.

Although shown separately, some of the components of disc media markingdevice 105 may be implemented in an application specific integratedcircuit (ASIC). Additionally, a system bus (not shown) typicallyconnects the various components within disc media marking device 105. Asystem bus may be implemented as one or more of any of several types ofbus structures, including a memory bus or memory controller, aperipheral bus, an accelerated graphics port, or a local bus using anyof a variety of bus architectures. Furthermore, disc media markingdevice 105 may share a system bus with a host processor.

Exemplary ODD Embodiment

FIG. 2 shows an exemplary embodiment of the ODD system 170 shown inFIG. 1. The ODD system 170 comprises an optical pickup unit (OPU)assembly 200 that includes a sled 203, a laser 205, a photo sensor 207,an objective lens or optics 209, and an actuator 211. The actuator 211responds to an input voltage (or current) to cause the optics 209 tomove the focal point.

For purposes of illustration, the optics 209 are carried by lenssupports 213(1), 213(2). The optics 209 are configured for travel (i.e.adjustment of the focal point) along a “z” axis 215 perpendicular to anoptical disc 217. A laser beam 219 is generated by the laser 210 andshown onto (reflected on) a label side surface 221 of optical disc 217.The laser beam 219 creates laser marks that correspond to label imagedata to render an image of the label side of the optical disc 217.

The ODD system 170 includes a spindle motor 223, a sled motor 225, and acontroller 230. In general, controller 230 may be implemented as aprinted circuit board employing a combination of various componentsdiscussed above with respect to the disc media marking system 100 ofFIG. 1. Accordingly, controller 230 includes a processor 235 forprocessing computer/processor-executable instructions from variouscomponents stored in a memory 240. Processor 235 is typically one ormore of the processors 115 discussed above with respect to the discmedia marking system 100 of FIG. 1. Likewise, memory 240 is typicallythe non-volatile memory 130 and/or firmware 140 of disc media markingsystem 100 of FIG. 1.

Controller 230 further includes a phase lead filter 245, a calibrationmodule 250, a measurement module 255, and a printing module 260.

Drivers 278, including a laser driver, sled driver, and spindle driverare stored in memory 240 and executable on processor 235. Although thesecomponents are represented in the FIG. 2 embodiment as softwarecomponents stored in memory 240 and executable on processor 235, theymay also be implemented as firmware or hardware components.

In general, a spindle driver drives the spindle motor 223 to control arotational speed of optical disc 217 via a spindle 280. The spindledriver operates in conjunction with a sled driver which drives the sledmotor 225 to control coarse radial positioning of OPU assembly 200 withrespect to disc 217 along a sled drive mechanism 283. In a focusposition measurement implementation, the sled 205 of the OPU assembly200 is moved along the sled drive mechanism 283 to various radiipositions of optical disc 217.

In a label surface marking implementation, the rotational speed of disc217 and the radial position of OPU assembly 200 are controlled such thatlaser marks are written on the disc 217 as the label side surface 221moves past the laser beam 219 at a constant linear velocity.

A laser driver controls the firing of laser beam 219 to write lasermarks corresponding to a label image onto the label side surface 221.Additionally, the laser driver controls the intensity of the laser beam219 to read data maintained on the data side 287 of the optical disc 217when the disc is positioned such that the data side 287 passes over thelaser beam 219. In certain cases, the same side is used for data andlabeling.

Photo sensor 207 provides laser focus feedback to the laser driver. Inthis example, photo sensor 207 is comprised of four individual sensorquadrants; quadrants A, B, C, and D. Quadrants A, B, C, and D areconfigured to measure reflected light independent of one another. Inparticular, voltage is measured by the quadrants A, B, C, and D. Whenthe sum of measured voltage of the quadrants A, B, C, and D are at arelative maximum, it is an indication that the objective lens is at alocation on the “z’ axis that places the laser beam in focus.

Furthermore, photo sensor 207 may be configured to the controller 230,where photo sensor 207 allows the controller 230 to recognize patternson the optical disc 217 as it rotates. This pattern recognition isfurther discussed below.

A driver for actuator 211 is included among the drivers 278. Theactuator driver is executable on processor 235 to adjust an actuatorinput signal source 293 which provides an input to actuator 211.Actuator driver further accounts for any offset values to compensate fordifferent rates of sweeping of OPU assembly 200 as performed by actuator211. Furthermore, the actuator driver may allow for a DC voltage offset.As discussed further below, the DC voltage offset is used to provideconsistent time period of in focus measurement per particular sweepingfrequency during a calibration implementation. For each sweepingfrequency there is a DC voltage offset that provides that in focus takesplace consistently per a particularly time period. The DC voltage offsetmay be a delay or advance in the voltage cycle.

In one implementation of the data profile, a voltage data look-up table296 is configured to store input voltages that are provided to source293. When source 393 is voltage source, table 296 stores DC voltageoffset values to compensate for and particular to specific sweepingfrequencies. Furthermore, table 296 stores particular locations on anoptical disc corresponding to appropriate input voltage, sweepingfrequency, and offset that allow the OPU optics or objective lens 209 tobe placed in proper focus. Table 296 is further discussed below. Acalibration table 298 is further included to provide, create, and storeoffsets values that are determine in a calibration procedure, where theoffset values are particular to sweeping frequencies.

Computing device interface 299 interfaces the controller 230 of the ODDsystem 170 with another electronic or computing device to receive labelimage data or a label file (not shown). The computing device interface299 can be implemented as an ATAPI (Advanced Technology AttachmentPacket Interface), which is one of many small computer parallel orserial device interfaces. Another common computer interface is SCSI(small computer system interface), which is a generalized deviceinterface for attaching peripheral devices to computers. SCSI definesthe structure of commands, the way commands are executed, and the waystatus is processed. Various other physical interfaces include theParallel Interface, Fiber Channel, IEEE 1394, USB (Universal SerialBus), and ATA/ATAPI. ATAPI is a command execution protocol for use on anATA interface so that CD-ROM and tape drives can be connected via thesame ATA cable with an ATA hard disc drive. ATAPI devices generallyinclude CD-ROM drives, CD-recordable drives, CD-rewritable drives, DVD(digital versatile disc) drives, tape drives, super-floppy drives (e.g.,ZIP and LS-120), and the like.

Operation

Calibration Implementation

FIG. 3 shows timeline curves used in calibrating a phase delay of theactuator 211 which controls the focal position of the optics 209. Thephase delay is typically measured in degrees with respect to an ACsignal, and represents a phase delay between application of the ACsignal to the actuator 211 and an associated response in the focal pointof the optics 209. The calibration may be performed while an opticaldisc is spinning or stationary, and may be performed when the sled 203,optics 209 and laser 205 are at any desired radial distance from thecenter of the optical disc. Where the disc is stationary, thecalibration process may be more accurate, since variations in the discwill not result in error in the calibration calculation.

In some applications, since phase delay is influenced by the frequencyof the AC component of the voltage applied to the actuator 211, it maybe desirable to calibrate the phase delay of the actuator 211 for avariety of frequencies. A calibration phase shift for the actuator 211for several frequencies may be useful. To see why this is the case, wenote that in FIG. 10 a method of printing an image on an optical isdescribed, wherein the optical disc is spun more rapidly when innerportions of the disc are printed and more slowly when outer portions ofthe disc are printed, thereby maintaining a constant linear speed.Accordingly, a higher-frequency AC signal may be provided to theactuator 211 when some portions of the disc are printed and alower-frequency AC signal may be provided to the actuator 211 when otherportions of the disc are printed. Accordingly, it can be beneficial tocalibrate the actuator at both lower and higher frequencies, to discoverthe delay between signal and response at both lower and higherfrequencies.

Referring to graph 300 of FIG. 3, waveform 302 represents the ACcomponent of a composite AC and DC signal which may be applied to theactuator 211 (FIG. 2). Accordingly, the waveform 302 drives the focaloptics 209 (FIG. 2) back and forth through a subset of the focal rangeof the optics 209. Where the AC component rides on a DC component ofappropriate magnitude, the actuator 211 drives the focal optics 209alternately into and out of focus on a surface, such as the disc surface221. While a triangle wave 302 is illustrated, any AC signal could beused.

Referring to graph 304 of FIG. 3, waveform 306 represents the distancebetween the focal point of the optics 209 and a fixed location 409, suchas the origin of the laser beam (FIG. 2). The waveform 306, showing thefocal point resulting from positioning of the optics 209, tracks (i.e.follows or responds to) the waveform 302, which represents the inputsignal given to the actuator 211 (FIG. 2) which controls the location ofthe optics 209. Note that the input signal 302 to the actuator leads thefocal point waveform 306 in phase. The degree to which the input signal302 leads the movement of the actuator 211 and optics 209, for a givenfrequency of the input signal 302, is measured during a calibrationprocess, as will be seen. The phase angle by which the actuator lagsbehind the input signal 302 is seen at 308, and is typically expressedin degrees or as a time delay. By measuring this phase lag, bettercontrol over the actuator is possible. Accordingly, the phase lag may bedetermined, as seen below.

Graph 310 of FIG. 3 expresses the output of the SUM signal from the quadsensor 207 (FIG. 2) The SUM signal peaks 312-318 indicate that the focaloptics passes through the focal point once during each movement 320-326of the optics; i.e. as the optics moves out and back, it is momentarilyin focus once each direction. Note that the distance between all of theSUM peaks 312-318 is not the same. This is because the DC component ofthe waveform 302 is such that the focal point is somewhat nearer one endor the other of the travel path of the actuator 211 and optics 209. Thatis, the focal point is nearer one end of the range over which the opticsfocuses than the other end. More particularly, it can be seen thatvertical lines extending from the SUM signal peaks 312-318 intersect thegraphical description of the actuator movement 320-326 along line 328.Thus, line 328 indicate the point in each line segment 320-326 whereinthe optics is in focus. The line 328 is offset from a line 330representing a center-line of the travel path of the optics. This offsetmay be removed by adjusting the DC component of the signal 302 suppliedto the actuator. That is, by changing the range over which the opticsfocuses periodically, the optics may be made to come into focus at themiddle of that range. Thus, where the DC offset applied to signal 302 iscorrectly adjusted, the line 330 will indicate the point in each linesegment 320-326 wherein the optics is in focus.

Graph 332 of FIG. 3 shows the four SUM signal peaks 334-340 separated bya uniform distance. This resulted by adjustment of the DC component tothe signal 302 applied to the actuator 211. That is, since the actuator211 moves the optics 209 back and forth along a focal range, byadjusting the DC component applied to the actuator 211, the optics maybe made to come into focus at the center of that range. The evenlyspaced SUM peaks 334-340 result when the DC component to signal 302 iscorrectly adjusted.

The phase lag of the actuator can be determined by observing the lagtime between one of the SUM peaks and the signal applied to the actuator211 (FIG. 2) which caused that SUM peak. For example, SUM peak 338 isdirectly below the mid point of actuator 211 and optics movement 324.However, the voltage that resulted in the actuator 211 being at themidpoint of it travel range is voltage 342. Voltage 342 is separatedfrom actuator location 344 by time 346. Since the time 346 is known, thephase lag of the actuator 211 can easily be determined. Accordingly, theactuator 211 has been calibrated (i.e. phase lag determined) for thefrequency of the signal 302.

The actuator 211 can also be calibrated for additional frequencies, asneeded. FIG. 6A indicates a more detailed view of the calibration table298 of FIG. 2 wherein the actuator 211 has been calibrated for fourfrequencies, ranging from 2 to 5 Hz. For each frequency, a phase shiftcorresponding to a lag time associated with the operation of theactuator is shown. In an optional feature, the location on the discwherein the calibration was performed may be recorded. As seen above,the actuator may be calibrated with the disc stationary, or in somecases, with the disc moving.

FIG. 4A shows various locations on the label region 400 of an opticaldisc where focal measurements may be made. Using the focal measurements,the look-up table of FIG. 6B may be generated. Using the look-up tableof FIG. 6B, having actuator voltage input information associated with anumber of locations on the disc, the optics 209 may be kept in focuswhile applying an image to the surface 221 (FIG. 2) of an optical disc.Optical disc 400 illustrates exemplary locations wherein focalmeasurements may be made, i.e. exemplary locations wherein an actuatorinput voltage which will result in actuator focus. Measurements may bemade at various radial distances within the optical disc 400. Forexample, measurements yielding voltage levels required to cause theactuator 211 to focus the optics 209 may be made at an inner radiallocation 402, an intermediate radial location 404, and an outer radiallocation 406.

For each particular radius position, a measurement may be made for anynumber of sectors of the disc. In an exemplary implementation, the discis divided into eight sectors (wherein an exemplary sector 408 isillustrated). A zero reference point is established, where zero and 360degrees are the same point.

FIG. 4B shows an exemplary implementation for generating a voltage datalook-up table 298 (FIG. 2) wherein the voltage data look-up tableprovides voltage levels for operation of an actuator which result infocus of the optics on a plurality of locations within a label region ofan optical disc. Graph 410 includes a curve 412 which shows anexaggerated curvature of a surface 221 (FIG. 2) of a disc 217 (FIG. 2).In particular, curve 412 shows how the distance from a fixedlocation—such as the tip 409 of the laser (i.e. the tip of the laserdevice generating beam 219)—to the surface 221 of the disc 217 can varyas the disc rotates over 360 degrees. For example, the disc is a greaterdistance 414 from the fixed location 286 after turning approximately 90degrees, and a lesser distance 416 turning 270 degrees.

Graph 418 illustrates an AC component of an input voltage which may beapplied to the actuator 211. Four triangle waves 420 ramp voltage intothe actuator 211 to cause the optics 220 to pass through a focal rangeeight times, resulting in eight SUM signal peaks indicating that theoptics are in focus eight times per revolution. Eight SUM peaks aretypically necessary to create the look-up table 298 (FIG. 2), andadditional SUM peaks, resulting from a greater AC frequency in thesignal 418 input to the actuator 211, is advantageous.

Graph 424 illustrates triangle waves 424 forming an AC component of aninput voltage having a phase shift according to calibration of theactuator 211, such as according to the discussion of FIG. 3.

Graph 426 illustrates eight SUM peaks, associated with the four trianglewaves. Each SUM peak is a local maximum of the data coming from the SUMsensor 207 (FIG. 2). Each SUM peak is associated with an input voltagewith was sent to the actuator, and which resulted in the SUM peak. Forexample, SUM peak 428 is associated with a voltage 430 in graph 418.Accordingly, when the voltage associated with location 430 was appliedto the actuator 211, when the disc was oriented at approximately 170degrees, the optics were focused on point 432 on the surface 211 (FIG.2) of the disc 217 (FIG. 2).

However, because graph 418 is phase-adjusted for the phase lag of theactuator 211, a voltage level which compensates for the phase lag of theactuator can be associated with SUM peak 428. Voltage 434 may beslightly more accurate than voltage level 430, because graph 422 isphase-adjusted for the phase lag of the actuator.

FIG. 5 replicates the curve 410 of FIG. 4, showing the distance from afixed location to an annulus defined on the surface of a disc over 360degrees of rotation. Below the curve 410 is a further exemplaryimplementation of the data profile, including an exemplary piece-wisecontinuous function 510 wherein the voltage levels which resulted in theSUM peaks are seen at 515(1) through 515(8). Between the points 515 ofthe curve 510 are interpolated voltage values. The values may beinterpolated by a first order linear function, a second order quadraticfunction or any other desired technique. For example, the any desiredpoint on the curve 510 may be calculated by operation of a Fourierseries, a polynomial series or similar technique.

Curve 510 may include a phase offset value 512 equivalent to phase delay346 (FIG. 3) to account for the inherent lag of the movement of actuator211 and optics 220 in response to input voltage.

FIG. 6A shows calibration table 298. The calibration table associates afrequency of an AC component of a signal applied to the actuator with aphase offset. This data may be obtained according to the discussion ofFIG. 3. The calibration table 298 may be included as part of memory 298as shown in FIG. 2. The calibration table 298 includes a sweep frequencycolumn 600 and a degree offset column 605. Sweep frequency values areparticular to measurement locations on the optical disc as representedin column 610 and have particular offset values represented by (P, whichcorresponds to a calculated phase offset performed in calibration andused in measurement procedures. Values of column 605 are determined fromthe calibration procedure described above.

FIG. 6B shows an implementation of a data profile configured as avoltage data look-up table 296. The voltage data look-up table 296 maybe included as part of memory 298 as shown in FIG. 2. An optical discmay be logically segmented into sectors, as illustrated in FIG. 4A.Typically, eight or more sectors are defined. As illustrated in table296, column 615 defines particular sectors of the optical disc, andspecifically segments the optical disc into 8 sectors. Each sectorcomprises 45 degrees of the 360 degrees that represent the optical disc.Each sector is further defined by a radial position from the opticaldisc's hub. Column 620 represents an inner radial position. Column 625represents a middle radial position. Column 630 represents an outerradial position.

In the measurement procedure described above, a voltage and phase delayφ may be calculated for each particular sub-sector as defined by anangular disc sector (i.e., column 615), and further defined by radialposition (i.e., columns 620, 625, and 630). At each cell entry shown intable 296 a particular voltage value “V” is provided that drives theactuator to a focus position and may include a phase delay φ. The cellvalues are derived from the measurement procedure described above.

Voltage values of adjacent cells may be averaged to arrive at anintermediate value for a position between the adjacent cells. Forexample, a voltage value at a particular radius position may be averagedwith a voltage value of a cell at an adjacent radius position, where thecells share the same disc sector as represented by column 615 (i.e.,going across a row cell position). Alternatively, a voltage position ata particular sector value may be averaged with a voltage of cell at anadjacent sector value, where the cells share the same radius position(i.e., going up/down columns 620, 625 or 630 cell positions).

When applying compensation, a circuit such as digital phase lead filtermay be used. Referring now to FIG. 2, phase lead filter 245 is shown asincluded in controller 235. The phase lead filter 245 may be implementedin hardware, firmware, and/or software. As input voltage is driven intovoltage source 293, the phase lead filter 245 adjusts for phase delay φ.

Focus Peaks

Peaks 310 may be calculated based on a relative maximum amount of lightmeasured by photo sensor 215 of FIG. 2. When photo sensor 207 measures amaximum of light, in focus situations exist. Photo sensor 207 may beoverly sensitive at a center of in focus, therefore measurement may bemade at the sides of the center, and the measured times average toarrive at a center point.

Alternatively to a photo sensor measuring the light, in focusdetermination may be made by controller 230 of FIG. 2 recognizing apattern on an optical disc. Photo sensor 207 or other component of anoptical pickup unit may be configured to controller 230 allowingcontroller 230 to recognize a pattern on the optical disc.

FIG. 7 shows an optical disc 700 with a recognizable pattern. The labelside of optical disc 700 is particular marked to allow a controller ofan ODD to recognize the pattern when the optical disc is spun and theOPU objective lens is in focus. Disc 700 may have clear coating on itssurface, and the pattern may be marked inside the clear coating; howeverit is contemplated that the pattern is read at the surface of the clearcoating where marking implementation is performed.

Optical disc 700 is spun in a counter clockwise direction as indicatedby arrow 705. An outer diameter section 710 of optical disc 700 ismarked with a pattern 715. In this example, a spoke pattern is shown andmay populate the entirety of outer diameter section 710. Likewise aninner diameter section 720 is marked with a spoke pattern 725 which maypopulate the entirety of inner diameter section 720.

As optical disc 700 is spun, spoke patterns 715 and 725 are read if anobjective lens such as objective lens 209 of FIG. 2 is in focus. OPU 200of FIG. 2 may be placed over either outer diameter section 710 to readspoke pattern 715, or placed over inner diameter section 720 to readspoke pattern 725.

Objective lens 209 is swept by actuator 211, and spoke patterns 715 and725 come into and out of focus (i.e. read by controller 230 of FIG. 2).Typically, a square wave is seen at controller 230 of FIG. 2 when thespoke patterns 715 and 725 are read. When out of focus situations exist,no pattern or signal is seen at controller 230.

FIG. 8 shows an exemplary process 800 for calibration of an actuator 211(FIG. 2). The calibration process determines a phase lag by whichresponse by the actuator is delayed after application of an inputvoltage (or current). The process 800 should be considered in view ofthe illustrations and discussions of FIG. 3, wherein calibration of theactuator was previously discussed.

At block 802, the OPU assembly, and in particular the laser, optics andsensors, is moved to a location near the hub of the optical disc.

At block 804, in one embodiment, the optical disc is maintained astationary condition during the calibration procedure. In general,rotation of the disc during the calibration process changes the positionat which the optics is focusing (if the optics are focused at the disc,which is convenient), and thereby reduces the accuracy of thecalibration.

At block 806, a particular frequency is chosen at which the actuatorsweeps the optics back and forth through the focal point in a directionperpendicular to the surface of the optical disc. The frequency may beselected to be similar to the anticipated frequency of the actuatorduring use. The calibration that is performed results in calculation ofa phase lag that is related to the chosen frequency of the AC signal.

At block 808, the AC signal at the chosen frequency is applied to theactuator. A DC component of the signal should be selected to result inthe optic moving back and forth through the focal point. Accordingly, asthe signal is applied, the actuator moves the optics back and forththrough the focal point, where the focal point is indicated by the SUMsignal peaks.

At block 810, the DC component to the actuator input signal is adjustedso that the SUM signal peaks are evenly spaced over 360 degrees. Byevenly spacing the SUM signal peaks, we know that the SUM signal peaksresult from voltage at a mid-point of the AC input signal to theactuator.

At block 812, a phase delay is calculated that is particular to thefrequency of the AC signal. The phase delay may be calculated by lookingat the SUM peaks, wherein the optics are in focus, and comparing theangular location of the SUM peaks to a voltage midpoint of the AC inputsignal.

At block 814, additional calibrations may be performed for any otherfrequencies such as those frequencies at which it is anticipated thatthe actuator may be driven.

FIG. 9 shows an exemplary process 900 for measurement of a specificoptical disc. During the process 900, a data profile particular to thespecific disc, may be configured. In different implementations, the dataprofile may be a voltage data look-up table 296 (FIG. 2) or a function510 (FIG. 5) which is used to calculate a signal, such as a voltage orcurrent level, for input to an actuator. Such a signal results inoperation of the actuator consistent with movement of the optics tofocus on the label region of the optical disc. Measurement may beperformed for various locations of the label region of the optical disc.The greater the number of measurements that are determined, the moreaccurate the mapping of the contour of the surface of the optical disc.As will be seen, actuator control signals for areas between measuredlocations may be estimated by interpolation from locations wherein thesignal which results in correct actuator performance, i.e. wherein theoptics focuses on the label region, are known.

At block 902, a voltage input or signal to the actuator is selected suchthat its AC component has a frequency that results in the actuatormoving the focal optics back and forth through the focal point at leasteight times per every revolution (rotation) of the optical disc. The infocus positions are recognized by a photo sensor, such as the SUMsignal, or by recognition of a pattern marked on the optical discsurface.

At block 904, the amplitude of the AC component and/or DC offset to thesignal is adjusted to result in movement of the optics back and forththrough the focus point according to the AC component.

At block 906, as the optical disc is turned, the input voltage or signalis applied to the actuator.

At block 908, a voltage which was applied to the actuator and whichresulted in a SUM signal peak is recorded, such as into a look-up table.Alternately, the voltage which result in SUM signal peaks may be used toform a piece-wise continuous function, such as that seen in FIG. 5. Thevoltage levels may similarly be used to generate coefficients (such asfor a Fourier series or a polynomial series) which can be used togenerate any desired point along the continuous function. By generatingany desired point along the function, or by consulting the voltagelook-up table, a voltage level which puts the optics into focus at anylocation on the label surface of the optical disc may be obtain.

At block 910, where a look-up table is used, additional information isadded to the look-up table that associates (links) the record voltagevalues, with an associated angle (sector) and radial position.

At block 912, the recorded voltage may be associated with a phase shiftor lag time that corresponds with a lag time that is associated with theoperation of the actuator. Accordingly, the voltage look-up table and/orfunction (e.g. the function of FIG. 5) may be altered to account for thephase shift. For example, the voltages of curve 422 (FIG. 4) may be usedrather than the voltages of curve 418 (FIG. 4).

FIG. 10 shows an exemplary process 1000 for printing or marking a labelside of an optical disc. Labeling may be performed using the disc mediamarking system shown in FIG. 1. Labeling is performed using data profileassociated with the specific disc to be labeled, wherein the dataprofile was obtained by method 900, above. The data profile providesinformation needed to provide input to the.

At block 1002, printing of an image is performed within the label regionof the optical disc. The printing may be performed by focusing a laserusing the focal optics 220 on a photo sensitive material within thelabel region. The label region of the disc will have previously beenmeasured to for creation of a data profile (e.g. a voltage data storedin a look-up table) to facilitate maintaining optical focus during thelabeling process.

At block 1004, during the labeling process, the data profile, such as avoltage data look-up table 296, is continuously referred to for a signalfor application to the actuator to move the optics into focus for eachlocation on the optical disc.

At block 1006, in one embodiment, an interpolated signal value may becalculated for a given location within the label region using signalinformation related to adjacent location(s) on the label region. Forexample, optionally at block 1008, signal data associated with differentdisc sectors may be interpolated. Similarly, at block 1010, optionally,signal data associated with different radial distances may beinterpolated. In all cases, interpolation may be done with first orhigher order equations, such as linear approximations, spline curvefits, etc.

At block 1012, in an optional implementation, the phase of an ACcomponent of a signal sent to the actuator is adjusted to compensate fora phase-lag in the response of the actuator. In a first option, at block1014 the AC signal sent to the actuator is processed by a phase leadfilter 245 (FIG. 2). The phase lead filter provides the actuator with asignal which will position the actuator while compensating for the phaselag of the actuator. In a second alternative, at block 1016 the phaselead filter is directed to filter for a variety of different actuatorfrequencies, depending on the frequency of the AC component to be inputto the actuator.

Although the invention has been described in language specific tostructural features and/or methodological acts, it is to be understoodthat the invention defined in the appended claims is not necessarilylimited to the specific features or acts described. Rather, the specificfeatures and acts are disclosed as exemplary forms of implementing theclaimed invention.

1.-62. (canceled)
 63. A method comprising: generating a data profileadapted to provide signals to operate an actuator to focus an opticalmechanism on an optically writable label region of an optical disc; and,forming an image on the optically writable label region of the opticaldisc using the optical mechanism as has been focused thereon by theactuator in accordance with the data profile generated.
 64. The methodof claim 63, wherein generating the data profile comprises configuring alook-up table with signal data associated with focusing on locationswithin the optically writable label region of the optical disc.
 65. Themethod of claim 63, wherein generating the data profile comprisesconfiguring a function to generate signal data, the function associatinglocations within the optically writable label region of the optical discwith appropriate signals.
 66. The method of claim 63, wherein generatingthe data profile comprises: applying an alternating current (AC)component of a signal of the actuator as the optical disc is rotated,the AC component causing the optical mechanism to pass through a focalpoint in both directs on each cycle of the AC component; and, recordinga voltage within a voltage data look-up table that was applied to theactuator and that was associated with a SUM signal peak resulting frompassage of the optical mechanism through the focal point.
 67. The methodof claim 63, further comprising calibrating the actuator in accordancewith the data profile.
 68. The method of claim 63, wherein generatingthe data profile comprises including data within the data profileassociated with at least two radial distances from a center of theoptical disc.
 69. The method of claim 63, further comprising: indexingthe data profile in accordance with an angular orientation of theoptical disc; and, retrieving data from the data profile in accordancewith the angular orientation of the optical disc during image formation.70. The method of claim 63, wherein forming the image on the opticallywritable label region comprises interpolating between data within thedata profile.
 71. A system comprising: first logic to generate the dataprofile adapted to provide signals to operate an actuator to focus anoptical mechanism on an optically writable label region of an opticaldisc; and, second logic to form an image on the optically writable labelregion of the optical disc using the optical mechanism as has beenfocused thereon by the actuator in accordance with the data profilegenerated.
 72. The system of claim 71, wherein the first logic is togenerate the data profile by configuring a look-up table with signaldata associated with focusing on locations within the optically writablelabel region of the optical disc.
 73. The system of claim 71, whereinthe first logic is to generate the data profile by configuring afunction to generate signal data, the function associating locationswithin the optically writable label region of the optical disc withappropriate signals.
 74. The system of claim 71, wherein the first logicis to generate the data profile by: applying an alternating current (AC)component of a signal of the actuator as the optical disc is rotated,the AC component causing the optical mechanism to pass through a focalpoint in both directs on each cycle of the AC component; and, recordinga voltage within a voltage data look-up table that was applied to theactuator and that was associated with a SUM signal peak resulting frompassage of the optical mechanism through the focal point.
 74. The systemof claim 71, wherein the second logic is to form the image on theoptically writable label region by interpolating between data within thedata profile.
 75. An optical disc drive comprising: an optical mechanismto form an image on an optically writable label region of an opticaldisc inserted into the optical disc drive; an actuator to focus theoptical mechanism on the optically writable label region of the opticaldisc in accordance with a data profile; and, a mechanism to generate thedata profile adapted to provide signals to operate the actuator to focusthe optical mechanism on the optically writable label region of theoptical disc.
 76. The optical disc drive of claim 75, wherein themechanism is to generate the data profile by configuring a look-up tablewith signal data associated with focusing on locations within theoptically writable label region of the optical disc.
 77. The opticaldisc drive of claim 75, wherein the mechanism is to generate the dataprofile by configuring a function to generate signal data, the functionassociating locations within the optically writable label region of theoptical disc with appropriate signals.
 78. The optical disc drive ofclaim 75, wherein the mechanism is to generate the data profile by:applying an alternating current (AC) component of a signal of theactuator as the optical disc is rotated, the AC component causing theoptical mechanism to pass through a focal point in both directs on eachcycle of the AC component; and, recording a voltage within a voltagedata look-up table that was applied to the actuator and that wasassociated with a SUM signal peak resulting from passage of the opticalmechanism through the focal point.
 79. The optical disc drive of claim75, wherein the mechanism is to generate the data profile by includingdata within the data profile associated with at least two radialdistances from a center of the optical disc.
 80. The optical disc driveof claim 75, wherein the mechanism is further to interpolate betweendata within the data profile.
 81. The optical disc drive of claim 75,wherein the mechanism is further to calibrate the actuator in accordancewith the data profile.
 82. The optical disc drive of claim 75, whereinthe mechanism is further to: index the data profile in accordance withan angular orientation of the optical disc; and, retrieve data from thedata profile in accordance with the angular orientation of the opticaldisc during image formation.